The stakes raised by a play-off final can induce the type of scenes now more associated with the away dressing room at the Amex Stadium, so Crystal Palace's season needs to be considered in context. Rewind to mid-August and the numbing deflation of a thrashing at Ashton Gate. Dougie Freedman's side propped up the fledgling Championship table and would go on to lose their next game, too, to loiter pointless at the foot. They had failed to win any of their last nine games of the previous season, their start the maintenance of established dismal form. From the outside looking in this appeared a team in freefall, their trajectory a nosedive.

And so now to May and bank holiday Monday at Wembley, and a meeting with Watford that will earn the victors upwards of £120m. Palace, whose highest finish over the previous five years had been 15th, ended their campaign fifth, overcame bitter rivals and a form team in Brighton & Hove Albion in the play-off semi-finals, and duly sold out their allocation of 33,000 for the showpiece in three days.

"The way we started, we'd never have thought we'd be in this position," says the goalkeeper Julián Speroni, the only survivor of the club's last spell in the top flight. "But this division is, well, competitive. The secret is never giving up: we believed we were on the right path, so we carried on and have turned things around."

That feels simplistic. In a wildly unpredictable second tier, Palace have sensed opportunity, let it slip more than once, but grabbed it again at the last. Their campaign rather typifies a division where Wolverhampton Wanderers, bolstered by parachute monies and aspirants to return to the elite at the first attempt, can instead sink without trace, while Blackburn Rovers spend £8m on one player, go through six managerial changes and end relieved to be only perilously close to the trapdoor.

Palace were interlopers among the clubs expected to challenge, a side expertly constructed on a relative shoestring by Freedman, supplemented by extravagant talents from a productive academy, and tweaked cannily by Ian Holloway. They actually go into Monday's match unbeaten in six with the manager insistent his players are "in the strongest place we've been all season". The hope is their timing is in.

Holloway had arrived from Blackpool in October, Freedman having opted to pursue a role at Bolton Wanderers despite instigating the revival after that horrific start, courtesy of four new signings and an emphasis on solidity, with an eight-match unbeaten run. The Scot's abrupt departure, so unexpected considering his apparent commitment to the overall project, along with four other members of his backroom staff might have unsettled, but the team he had moulded together had found their rhythm. The new manager won his first four games and Palace were top. "I'm just glad I didn't completely muck it up," says Holloway, whose delight at inheriting a first team boasting such collective quality – if not a squad of huge depth – has been obvious.

Speroni is one of the most consistent performers outside the elite. The player of the year, Mile Jedinak, has been a colossus in central midfield – "He's just so Australian," the manager says, reflecting upon his captain's competitive nature – with South Africa's Kagisho Dikgacoi having rediscovered the form interrupted by the Africa Cup of Nations. Glenn Murray, now cruelly sidelined with cruciate and cartilage knee damage, is the first Palace player to score 30 league goals in a season since Johnny Byrne in 1961.Damien Delaney, Peter Ramage and, most recently, Danny Gabbidon have impressed in spells to offset the absence of the club captain, Paddy McCarthy, all season. Jonny Williams, the next great hope from the academy, is now a Wales international, Joel Ward is destined to be a Premier League right-back, and Yannick Bolasie has that wonderful blend of lavish skill and unpredictability to dazzle when focused.

Then, of course, there is Wilfried Zaha. The winger was unplayable, all extravagant step-overs and blistering pace, to earn a first England cap in the autumn even if his displays did dip marginally after the completion of his £15m move to Manchester United as opponents doubled up on him as a matter of course. But, as a loanee, he remains capable of scorching all-comers as Brighton discovered in the second leg of the semi-final.The Nike boot deal, and indeed Monday's hospitality box at the national stadium supplied by his boot manufacturers, reflect a raised profile. Surrendering a player who has been at Palace for a decade will be "like losing a family member", Holloway says.

"By the time he leaves for United he'll have played almost 150 games for this club," Steve Parish, the co-chairman, says. "He's had a dip in a few matches, but he's only 20 and I've never seen his effort waver. Even Messi has the odd bad game." It was Zaha's smile that illuminated the Amex.

Holloway's dancing did likewise in the visitors' dressing room post-match. He suffered following a fans' favourite in Freedman, and took the brunt of the nine-game winless streak in the spring that cost Palace automatic promotion, though his ability to coax that display at Brighton from his players demonstrated his pedigree, with this his third play-off final in the past four years. "He knows what he's doing, a very intelligent guy," Speroni says. "That run was difficult, but there had been so many changes at the club since Dougie left, and all that uncertainty seemed to catch up with us."

"It's difficult coming into a club where the team has been successful, and he was walking on eggshells a bit," Parish says. "The bad run might actually have made him because he decided: 'I might as well be myself.' At Brighton we saw the kind of manager Ian is: who else would have made those substitutions at 0-0, away from home in a game that could go to extra-time, and be as bold as he was? The shape, the discipline: they were all superb. The manager took a lot of stick but has come through it, and the team have come together as a group."

Promotion would represent eye-catching reward and allow for further progression off the pitch, not least injecting momentum into the owners' plans to redevelop Selhurst Park. "The four gentlemen who own this place want to get us up and into a beautiful new stadium," Holloway says. "The prize is bigger now than it's ever been. The others [clubs] are getting so rich and, however deep my owners' pockets are, they'll never be able to bridge the gap just themselves. So this is a chance. I want to try to help build something. Now I'm asking for one more performance. Let's go out and have a go."